Pyrite records fluid evolution: sulfur sources controls on arsenic speciation and zonation
Abstract
Zoning and speciation of arsenic (As) in pyrite are used to infer changes in the chemical composition of hydrothermal fluids and conditions of ore deposit forma-tion. Yet, the processes controlling the distribution and oxidation state of As during pyrite formation are poorly understood. We report the results of experiments designed to test the capacity of pyrite to record changes in fluid composition under dynamic reaction conditions. When pyrite seeds were exposed alternately to As-bearing and As-free fluids, concentric As-rich (≤6.0 wt. % of As1−) and As-free pyrite overgrowths formed when native S was used as the sulfur source. In contrast, a sodium thiosulfate source produced randomly oriented aggregates of concentrically zoned microparticulate (∼1 μm) As-bearing pyrite (
Fields of Study & Subjects
Metal Extraction and Bioleaching
Arsenic contamination and mitigation
Mine drainage and remediation techniques
Publication details
- Journal / source
- Geochemical Perspectives Letters
- Publisher
- European Association of Geochemistry
- Volume
- 38
- Pages
- 53–59
- Publication date
- 1 January 2026
- Language
- EN